Influence of Crop Age on Nutritional Quality and Hydrogen Cyanide Levels of Roots from Popular Coastal Kenyan Cassava Varieties

The research activities were funded by National Commission for Science, Technology and Innovation (NACOSTI) 2015/2016 FY , laboratory reagents were funded by East African Agricultural Productivity Project (EAAPP) Abstract Cassava is an important crop in coastal Kenya commonly harvested at 12 months after planting but earlier during food shortages. There is limited information that addresses the effect of early harvesting on root quality especially for newly released varieties. Varieties Tajirika, Karembo and Kibanda Meno (roots) were harvested at different ages from Research Centres, studied for nutritional quality and hydrogen cyanide levels for safe utilization. Results showed significant (p < 0.05) interaction effect of varieties and crop age on studied nutrients. Karembo and Tajirika had peak dry matter of 43.42% and 41.42% respectively at 12 months while the peak for Kibanda Meno was 44.99% at 9 months. Mean starch content varied with variety; Karembo (91.3%), Kibanda Meno (93.4%), and Tajirika (85.5%). Karembo and Tajirika had peak carbohydrates at 12 months while the peak for Kibanda Meno was at 9 months. Vitamin C was highest at 6 months for Karembo (6.4 mg/100g) and Kibanda Meno (66 mg/100g). Tajirika had highest vitamin C (7.0 mg/100g) at 9 months. Iron was peak at 3 months for Karembo (3.63 mg/100g) and Tajirika (5.33 mg/100g) but at 9 months for Kibanda Meno (7.12 mg/100g). Peak Zinc was 2.1 mg/100g for Karembo at 6 months while for Kibanda Meno (1.94 mg/ 100g) and Tajirika (1.75mg /100g) at 12 months.  Hydrogen cyanide increased from 8.6 to 9.3 mg/kg in Karembo between 9 and 12 months, it decreased from 7.8 to 5.2 mg/kg and from 5.1 to 4.5 mg/kg in Tajirika and Kibanda Meno, respectively. Harvesting of cassava roots should be staggered across crop ages to maximize on peaks of different root nutrients and processing is important. Keywords: Cassava varieties, roots, nutrients, hydrogen cyanide, months after planting DOI : 10.7176/FSQM/88-04 Publication date :July 31 st 2019